KR20050045433A - Display apparatus - Google Patents

Abstract

Disclosed is a display device that can reduce power consumption without lowering overall brightness. The display device includes a light generator that generates a first light and a display that displays an image by receiving a first light or a second light provided from the outside. The sensing unit outputs a sensing signal corresponding to the light amount of the second light incident from the outside to the display unit, and the first driving unit driving the light generating unit turns on or off the light generating unit in response to the sensing signal from the sensing unit. Therefore, power consumption can be reduced without lowering the overall brightness of the display device.

Description

Display device {DISPLAY APPARATUS}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly, to a display device capable of reducing power consumption without lowering the overall brightness.

In general, a liquid crystal display device includes a liquid crystal display panel that displays an image using light. The light may be external light provided from the outside of the liquid crystal display by the sun or an illumination lamp, or internal light generated by itself.

Light used in the liquid crystal display device is an important factor in determining the brightness of the screen of the liquid crystal display device. Accordingly, the liquid crystal display may further display an image by the external light where the external light is sufficient, but further include a backlight assembly to display the image by the internal light where the external light is insufficient.

About 70% of the power consumed to drive the liquid crystal display is consumed in the backlight assembly. In particular, portable devices requiring high power savings such as mobile phones, notebook computers, and PDAs are urgently required to reduce power consumption in the backlight assembly.

When the power provided to the backlight assembly is reduced in order to reduce the power consumption of the liquid crystal display, the amount of internal light emitted from the backlight assembly is reduced, thereby lowering the overall brightness of the liquid crystal display.

Accordingly, it is an object of the present invention to provide a display device that can reduce power consumption without lowering the overall brightness.

A display device according to an aspect of the present invention includes a light generator, a display, a detector, and a first driver.

The light generation unit generates a first light, and the display unit receives the first light or the second light provided from the outside to display an image. The sensing unit outputs a sensing signal in response to the amount of light of the second light incident from the outside to the display unit, and the first driving unit controls the driving of the light generating unit in response to the sensing signal.

According to such a display device, when the amount of light of the second light is greater than the reference value, the light generating unit is turned off so that the display unit displays an image with the second light. If the amount of light of the second light is smaller than the reference value, the display unit is turned on as the first light. Display the video. As a result, power consumption can be reduced without lowering the overall brightness of the display device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 2 is a view showing a first driver shown in FIG. 1.

Referring to FIG. 1, the liquid crystal display device 1000 according to an exemplary embodiment of the present invention may include a light generator 100 generating internal light L1 and a first controlling the driving of the light generator 100. The display unit 300 for displaying an image using the driving unit 200, the internal light L1 or the external light L2 from the outside, and a driving signal DS for driving the display unit 300. It includes a second driver 400 for outputting.

The liquid crystal display 1000 further includes a light detector 500 for outputting a photo current PC corresponding to the amount of light of the external light L2 provided from the outside to the display unit 100. Herein, the photocurrent PC increases in response to an increase in the amount of light of the external light L2 and decreases in response to a decrease in the amount of light of the external light L2.

The signal transmitter 600 compares the photocurrent PC output from the light detector 500 with a preset reference value and outputs first or second detection signals SS1 and SS2 according to a result. .

The first driver 200 controls the driving of the light generator 100 in response to the first or second detection signals SS1 and SS2 from the signal transmitter 600. The first driver 200 turns on the light generator 100 in response to the first detection signal SS1 output from the signal transmitter 500 when the photocurrent PC is smaller than the reference value. Outputs a turn-on voltage (Von). On the other hand, the first driving unit 200 in response to the second detection signal (SS2) output from the signal transmission unit 500 when the photocurrent (PC) is greater than the reference value the light generator 100 Output a turn-off voltage Voff to turn off.

Accordingly, the liquid crystal display device 1000 consumes power to drive the light generator 100 by turning the light generator 100 on or off according to the amount of light of the external light L2 provided from the outside. Can reduce the cost.

In addition, the first driver 200 may adjust the amount of light of the internal light L1 output from the light generator 100 according to the amount of light of the external light L2. That is, the first driver 200 reduces the amount of light of the internal light L1 by reducing the on voltage Von provided to the light generator 100 as the photocurrent PC increases from the reference value. Let's do it. In addition, the first driver 200 increases the amount of light of the internal light L1 by increasing the on voltage Von provided to the light generator 100 as the photocurrent PC decreases from the reference value. Let's do it.

2 is a plan view illustrating in detail the display unit illustrated in FIG. 1, and FIG. 3 is a cross-sectional view of the display unit illustrated in FIG. 2.

2 and 3, the display unit 300 includes a lower substrate 310, an upper substrate 320 facing the lower substrate 310, and a gap between the upper substrate 320 and the lower substrate 310. The liquid crystal layer 330 is interposed therebetween. The display unit 300 is divided into a display area DA displaying an image and a peripheral area PA adjacent to the display area DA.

In the display area DA, a plurality of pixel parts PP are entirely formed in a matrix form. The lower substrate 310 has a gate line GL, a data line DL orthogonal to the gate line GL, the gate line GL, and a data line corresponding to each of the plurality of pixel parts PP. A TFT 311 connected to the DL, a transmission electrode 312 coupled to the TFT 311, and a reflection electrode 313 formed on the transmission electrode 312 are provided.

The gate electrode 311a of the TFT 311 is connected to the gate line GL, the source electrode 311b is connected to the data line DL, and the drain electrode 311c is connected to the transmission electrode 312. ) And the reflective electrode 313.

In addition, the lower substrate 310 further includes a storage electrode 315 facing the transmissive electrode 312 and the reflective electrode 313 with an insulating layer interposed therebetween. The common voltage is applied to the storage electrode 315.

On the other hand, the upper substrate 320 is provided with a color filter 321 and a common electrode 322 consisting of R, G, B color pixels. The common electrode 322 is formed on the color filter 321 to face the transmissive electrode 312 and the reflective electrode 313.

Here, the region where the reflective electrode 313 is formed is a reflective region RA, and the region where the reflective electrode 312 is exposed because the reflective electrode 313 is not formed is a transparent region TA. The display unit 300 operates in a transmission mode in which an image is displayed through the transmission area TA using the internal light L1 provided from the light generator 100 (shown in FIG. 1), or is provided from the outside. The display device may operate in a reflection mode in which an image is displayed through the reflection area RA using the external light L2.

The peripheral area PA includes a second driver 400 including a gate driver 410 and a data driver 420. The gate driver 410 is electrically connected to the gate line GL, and outputs a gate driving voltage to the gate line GL in response to various control signals provided from the outside. The data driver 420 is electrically connected to the data line DL to output a data voltage to the data line DL.

As a result, when the light generator 100 is turned on in response to the light amount of the external light L2, the display unit 300 operates in the transmission mode using the internal light L1, and the light generator 100 is turned on. When is turned off, the display unit 300 operates in the reflection mode using the external light L2.

Here, although the display unit 300 is formed of the reflective area RA and the transmission area TA, the display unit 300 may include only the reflection area RA or the transmission area TA. This structure will be described in detail later with reference to FIGS. 8 to 10.

4 is a block diagram illustrating a display device according to another exemplary embodiment of the present invention. In FIG. 4, the same reference numerals are given to the same components as those illustrated in FIG. 1, and detailed description thereof will be omitted.

Referring to FIG. 4, the display device 1100 determines a first or second operation mode of the display unit 300 in response to the third or fourth sensing signals SS3 and SS4 from the signal transmitter 600. The apparatus further includes a mode switching unit 700 for outputting two mode selection signals FMS and SMS. The second driver 400 outputs first or second driving signals FDS and SDS in response to the first or second mode selection signals FMS and SMS output from the mode switching unit 700. Therefore, the display unit 300 displays an image in response to the first or second driving signals FDS and SDS.

The operation mode of the display unit 300 includes a transmission mode for displaying an image in the transmission area TA (shown in FIG. 3) and a reflection mode for displaying an image in the reflection area RA (shown in FIG. 3). The signal transmitter 600 outputs the third detection signal SS3 when the photocurrent PC is smaller than the reference value, and outputs the fourth detection signal SS4 when the photocurrent PC is smaller than the reference value. On the other hand, the mode switching unit 700 outputs the first mode selection signal FMS for selecting a transmission mode in response to the third detection signal SS3 and in response to the fourth detection signal SS4. The second mode selection signal SMS for selecting the reflection mode is output.

Thereafter, the second driving unit 400 receives any one of the first or second mode selection signals FMS and SMS provided from the mode switching unit 700, and then displays the display unit 300 in the transmission mode. Drive in any of the reflection modes.

5 is a graph showing changes in transmittance and reflectance according to the reflection voltage and the transmission voltage. The first graph TG shown in FIG. 5 shows a change in transmittance, and the second graph RG shows a change in reflectance.

Referring to FIG. 5, when about 4.2 V is applied to the liquid crystal layer 330 (shown in FIG. 3) provided in the transmission area TA (shown in FIG. 3), the liquid crystal display 1000 may have a maximum transmittance. (About 40%). Meanwhile, when about 2.6 V is applied to the liquid crystal layer 330 provided in the reflective area RA (shown in FIG. 3), the liquid crystal display 1000 has the maximum reflectance (about 38%).

As described above, since the transmission voltage showing the maximum transmittance and the reflection voltage showing the maximum reflectance are different from each other, the liquid crystal layer 330 provided in the reflection area RA and the liquid crystal layer 330 provided in the transmission area TA are different. It is desirable to apply different voltages. That is, about 4.2 V representing the maximum transmittance is applied to the liquid crystal layer 330 provided in the transmission area TA, and 2.6 V smaller than 4.2 V is provided in the reflection area RA. ) Is applied. Therefore, the transmittance and reflectance of the liquid crystal display device 1000 can be maximized.

FIG. 6 is a detailed block diagram illustrating the second driving unit illustrated in FIG. 1, and FIGS. 7A and 7B illustrate the first gamma circuit unit 430 and the second gamma circuit unit 440, respectively. 6 is a diagram illustrating a part of the gray scale resistor 470 included in the data driver 420 of FIG. 6.

Referring to FIG. 6, the second driver 400 includes a gate driver 410, a data driver 420, a first gamma circuit 430, a second gamma circuit 440, and a first common voltage generator 450. And a second common voltage generator 460.

The gray resistance unit 421 is built in the data driver 420. The gray resistance unit 421 has a structure in which a plurality of gray resistances are connected in series. For example, if the liquid crystal display 1000 displays an image in 256 (2 ⁸ ) gradations, the gradation resistor unit 421 includes 256 gradation resistors connected in series.

As shown in FIG. 8, a power supply voltage VDD is applied to one end of the gray resistance unit 421 and a ground voltage GND is applied to the other end. In accordance with the voltage division law, the connection portions of the respective gray scale resistors have different potentials, and the potentials of the connection portions of the gray resistors 470 are the first to 256th gray voltages VG0 to VG255.

The first gamma circuit unit 430 has a structure in which eight transmission resistors RT1 to RT8 are connected in series. The transmission resistances RT1 to RT8 have resistance values that can optimize the transmittance of the transmission mode shown in FIG. 5.

The first gamma circuit unit 430 is connected to the transmission resistances RT1 to RT8 in response to the first mode selection signal FMS provided from the mode switching unit 700 (shown in FIG. 4). The potential is output as transmission gamma (TGM1 to TGM8). The transmission gamma TGM1 to TGM8 is provided to the gray resistance unit 421, and the gray resistance unit 421 outputs a desired transmission gray voltage VT in response to the transmission gamma TGM1 to TGM8. As a result, the display unit 300 may operate in the transmission mode.

The second gamma circuit unit 440 has a structure in which eight reflection resistors RR1 to RR8 are connected in series. The reflection resistors RR1 to RR8 have resistance values capable of optimizing the reflectance of the reflection mode shown in FIG. 5.

In response to the second mode selection signal SMS provided from the mode switching unit 700, the second gamma circuit unit 440 converts the electric potential at the connection portion of the reflection resistors RR1 to RR8 into the reflection gamma RGM1. To RGM8). The reflection gamma RGM1 to RGM8 are provided to the gray resistance unit 421, and the gray resistance unit 421 outputs a desired reflected gray voltage VR in response to the reflection gamma RGM1 to RGM8. As a result, the display unit 300 may operate in the reflection mode.

The first common voltage generator 450 transmits the power supply voltage Vp provided from the outside in response to the first mode selection signal FMS provided from the mode switching unit 700 to optimize the transmission common. Output after converting to voltage (VTcom). The second common voltage generator 460 reflects the power voltage Vp optimized for the reflection mode in response to the second mode selection signal SMS provided from the mode switching unit 700. And then print it.

The gate driver 410 outputs a gate driving voltage Vg in response to various control signals CS from the outside.

According to another exemplary embodiment of the present invention, the liquid crystal display device 1100 turns on or off the light generator 100 according to the amount of external light L2, and at the same time, operates the display unit 300. You can switch modes.

That is, when the amount of light of the external light L2 is smaller than the reference value, the display unit 300 is operated in the transmission mode while turning on the light generator 100. In addition, when the light amount of the external light L2 is larger than the reference value, the display unit 300 is operated in the reflection mode while turning off the light generator 100.

9 to 11 are cross-sectional views illustrating various configuration examples of the liquid crystal display shown in FIG. 1. However, since the liquid crystal display shown in FIG. 9 employs the display shown in FIG. 3, detailed description of the display will be omitted.

Referring to FIG. 9, the liquid crystal display 1000 displays an image using the light generator 100 generating the internal light L1 and the internal light L1 or the external light L2 provided from the outside. It includes a display unit 300 to. Here, the light generator 100 is disposed below the display unit 300.

The light generator 100 includes a lamp 110 generating the internal light L1 and a light guide plate 120 to guide the internal light L1 to the display unit 300.

The lamp 110 includes a plurality of light emitting diodes (LEDs), and the light guide plate 120 has a rectangular plate shape and the lamp 110 is provided at one side thereof. The light guide plate 120 receives the internal light L1 through the one side to guide the internal light L1 to the display unit 100.

The lower portion of the light guide plate 120 is provided with a reflector plate 140 for reflecting light leaked from the light guide plate 120 toward the display unit 300, and the upper portion of the light guide plate 120 to improve the brightness and viewing angle of the light emitted from the light guide plate 120. Optical sheets 130 to be provided are provided.

The display unit 300 includes an upper substrate 320, a lower substrate 310 facing the upper substrate 320, and a liquid crystal layer interposed between the upper substrate 320 and the lower substrate 310. Not shown).

As shown in FIG. 3, the lower substrate 310 includes a reflection area RA and a transmission area TA. Therefore, the display unit 300 operates in a transmission mode for displaying an image by transmitting the internal light L1 provided from the light generator 100 or by reflecting the external light L2 provided from the outside. Operate in reflection mode to display images.

In this case, the liquid crystal display 1000 may turn the light generator 100 on or off according to the amount of light of the external light L2 provided from the outside. In addition, the display unit 300 operates in the transmission mode or the reflection mode in conjunction with the light generator 100 being turned on or off. Therefore, the power consumed to drive the light generator 100 can be reduced without lowering the overall brightness of the liquid crystal display device 1000.

Referring to FIG. 10, the liquid crystal display 1200 displays an image using the light generator 100 generating the internal light L1, the internal light L1, or the external light L2 provided from the outside. The display unit 301 and a transflective film 350 for transmitting the internal light L1 and reflecting the external light L2 are included.

The display unit 301 may be an upper substrate 320, a lower substrate 310 facing the upper substrate 320, and a liquid crystal layer interposed between the upper substrate 320 and the lower substrate 310. ) The display unit 301 is a transmissive display unit having only a transmissive electrode excluding a reflective electrode on the lower substrate 310.

The transflective film 350 is provided between the display unit 301 and the light generating unit 100 to transmit the internal light L1 output from the light generating unit 100, and is provided from the outside. The external light L2 is reflected.

Therefore, the display unit 300 operates in a transmission mode in which an image is displayed by using the internal light L1 passing through the transflective film 350 or the external light reflected by the transflective film 350. It operates in a reflection mode in which an image is displayed using light L2.

In this case, the liquid crystal display 1200 may turn on or turn off the light generator 100 according to the amount of light of the external light L2 provided from the outside. The power consumed to drive the light generator 100 may be reduced without lowering the overall brightness of the liquid crystal display device 1000.

Referring to FIG. 11, the liquid crystal display device 1300 displays an image using the light generator 101 generating the internal light L1, the internal light L1, and the external light L2 provided from the outside. The display unit 302 is included.

The display unit 302 is a reflective display unit consisting of only reflective electrodes except for a transmissive electrode. Accordingly, the display unit 302 operates in a reflection mode in which the external light L2 is reflected to display an image.

The light generating unit 101 is provided above the display unit 302, and is turned on when the light amount of the external light L2 provided to the display unit 302 is smaller than a reference value, thereby turning on the entirety of the display unit 302. Compensate so that the luminance does not deteriorate. On the other hand, the light generator 102 is turned off when the amount of light of the external light L2 is larger than the reference value.

In this case, in order to measure the light amount of the external light L2 by distinguishing it from the light amount of the internal light L1, the external light is linked with the light amount of the internal light L1 output from the light generator 102. It is preferable to measure the light quantity of (L2). That is, when a light detector (not shown) for detecting the light amount of the external light L2 is embedded in the display unit 302, the light detector includes the internal light L1 and the external light L2 together. Will receive. Since the light amount of the internal light L1 is predetermined, a value obtained by subtracting the light amount of the internal light L1 from the light amount detected by the light sensing unit is the light amount of the external light L2.

Therefore, the power consumed to drive the light generator 102 can be reduced without lowering the overall brightness of the liquid crystal display device 1200.

According to such a display device and a driving method thereof, the sensing unit outputs a sensing signal corresponding to the amount of external light incident from the outside into the display unit, and the first driving unit is a light generating unit that provides internal light to the display unit in response to the sensing signal. Turn it on or off.

Therefore, when the amount of external light is greater than the reference value, the light generating unit is turned off so that the display unit displays the image as external light. When the amount of external light is smaller than the reference value, the display unit displays the image as the internal light. As a result, power consumption can be reduced without lowering the overall brightness of the display device.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

1 is a block diagram of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a plan view specifically showing the display unit illustrated in FIG. 1.

3 is a cross-sectional view of the display unit illustrated in FIG. 2.

4 is a block diagram illustrating a display device according to another exemplary embodiment of the present invention.

5 is a graph showing changes in transmittance and reflectance according to the reflection voltage and the transmission voltage.

FIG. 6 is a block diagram illustrating in detail the second driver illustrated in FIG. 1.

FIG. 7A is a diagram illustrating the first gray voltage generator shown in FIG. 6.

FIG. 7B is a diagram illustrating a second gray voltage generator shown in FIG. 6.

8 to 10 are cross-sectional views illustrating various configuration examples of the liquid crystal display shown in FIG. 1.

<Explanation of symbols for the main parts of the drawings>

100: light generating unit 200: first driving unit

300: display unit 400: second drive unit

410: gate driver 420: data driver

430: first gray voltage generator 440: second gray voltage generator

500: light detector 600: signal transmitter

700: mode switching unit 1000: liquid crystal display device

Claims (14)

A light generator for generating first light; A display unit configured to display an image by receiving the first light or the second light provided from the outside from the light generator; A detector for outputting a detection signal corresponding to an amount of light of the second light incident from the outside to the display unit; And And a first driver configured to control driving of the light generator in response to the detection signal. The display device of claim 1, wherein the first driver turns on or off the light generator in response to the detection signal. 3. The light emitting device of claim 2, wherein the first driving unit outputs a first control signal for turning on the light generating unit when the amount of light of the second light is smaller than a preset reference value, and when the amount of light of the second light is larger than the reference value. And a second control signal for turning off the generator. The display device of claim 1, wherein the first driver adjusts an amount of light of the first light output from the light generator in response to the detection signal. The method of claim 4, wherein the first driving unit outputs a first control signal for reducing the light amount of the first light as the light amount of the second light is smaller than the predetermined reference value, the light amount of the second light is And a second control signal for increasing the amount of light of the first light by a larger value than the reference value. The display apparatus of claim 1, wherein the display unit is operated in a transmission mode for transmitting the first light through a transmission electrode to display an image and in a reflection mode for displaying the image by reflecting the second light through a reflection electrode. Display. The method of claim 6, wherein the second drive unit, A mode switching unit outputting first and second mode selection signals for determining a mode of the display unit in response to the detection signal; A first gamma circuit unit outputting a transmission gamma in response to the first mode selection signal; A second gamma circuit unit outputting a reflection gamma in response to the second mode selection signal; And And a gray scale resistor unit outputting a gray scale voltage to the transparent electrode in response to the transmission gamma and outputting a reflected gray voltage to the reflective electrode in response to the reflective gamma. The method of claim 7, wherein the first gamma circuit part comprises a plurality of transmission resistors connected in series, and outputs a potential at the point where the transmission resistors are connected as the transmission gamma, And the second gamma circuit part has a resistance value different from the transmission resistance, and is formed of a plurality of reflection resistors connected in series, and outputs a potential at the point where the reflection resistors are connected as the reflection gamma. The point of claim 8, wherein the gray resistance part includes a plurality of gray resistances, and outputs a potential corresponding to the transmission gamma among the potentials of the points at which the gray resistances are connected as the transmission gray voltage, and the point at which the gray resistances are connected. And a potential corresponding to the reflected gamma among the potentials of the output signal as the reflected gray voltage. The display device of claim 7, wherein the mode switching unit outputs the first mode selection signal so that the display unit operates in the transmission mode when the light amount of the second light is smaller than a preset reference value, and the light amount of the second light is greater than the reference value. If larger, the second mode selection signal for controlling the display unit to operate in the reflection mode. The display device of claim 6, wherein the display unit further comprises a storage electrode facing the transmissive electrode and the reflective electrode with an insulating layer interposed therebetween. The method of claim 11, wherein the second drive unit, A first common voltage generator configured to output a first common voltage to the storage electrode when the display unit is operated in the transmission mode; And And a second common voltage generator configured to output a second common voltage to the storage electrode when the display unit is operated in the reflective mode. The display apparatus of claim 1, wherein the display unit is a transmissive display unit formed of a transmissive electrode. And a transflective portion interposed between the display portion and the light generating portion to transmit the first light and reflect the second light. The display device of claim 1, wherein the display unit is a reflective display unit formed of a reflective electrode. And the display unit reflects the first light from the light generator and the second light provided from the outside to display an image.